Hewlett-packard Corporation

Hewlett-packard Company

J Daren Bledsoe

David Lynn Burton

Brian D Setterberg

David E Smith

Dennis Eugene Ochs

Howard E Hilton

Daniel J Powers

Edward L Feldhousen

Judith Cyrus

Steve Kootstra

David C Shultheis

Dan Jordan

Brian C Dunn

Art Burkhalter

Alan V Andresen

An ECG recorder and playback unit which includes software-implemented digital signal processing filters which compensate for phase and magnitude distortion occurring when an ECG signal is recorded on a Holter recorder and played back. This permits 'tuning' a recorder and playback unit which may be unrelated, as when made by different manufacturers. An impulse or step signal is recorded and played back to provide a system frequency response measurement. Coefficients for a digital correction filter are derived from the discrete Fourier transform of the impulse or step response and a desired system response. When recorded ECG data is played back, it is filtered on a substantially real-time basis with the digital correction filter to compensate for phase and magnitude distortion. Prior to recording, the high frequencies of the ECG signal are boosted to compensate for high frequency losses inherent in the recording and playing back of ECG signals. A calibration pulse and a system characterization pulse are derived by statistically selecting from a plurality of pulses and averaging the selected pulses in order to minimize the effects of noise and tape defects in the pulses. High frequency components of the ECG signal can be amplified prior to recording the signal. This results in decreased amplification, and therefore noise, when the recorded signals are played back. Cardiac pacer pulse detection is performed prior to the step of filtering the played back signal to optimize pulse detection.

Method and apparatus for boosting the amplitude of ECG signals within a

ECG recorder and playback unit

A defibrillator/monitor architecture is disclosed with a defibrillator-only mode of operation to provide for shocking a patient notwithstanding failure of the monitor subsystem. The defibrillator/monitor subsystem is partitioned into a defibrillator subsystem and a monitor subsystem. The defibrillator subsystem includes the patient charging circuits and other components necessary to carry out basic defibrillation. The monitor subsystem includes an ECG front-end, CRT display, data recorder and other features. In normal operation, the defibrillator subsystem relies on periodic ECG data ready interrupts from the monitor subsystem for system timing. In the event that the ECG interrupts do not arrive within a predetermined time limit, the monitor subsystem is presumed dead and the defibrillator subsystem switches to defibrillator-only mode of operation, in which system timing is provided by a local standby timer.

Integrated defibrillator/monitor architecture with defibrillator-only

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McMinnville, OR, United States of America

J Daren Bledsoe